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  <title>返回字符串所用字符的信息</title>
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  <div id="layout-content"><div id="function.count-chars" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">count_chars</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">count_chars</span> &mdash; <span class="dc-title">返回字符串所用字符的信息</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.count-chars-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>count_chars</strong></span>(<span class="methodparam"><span class="type">string</span> <code class="parameter">$string</code></span>, <span class="methodparam"><span class="type">int</span> <code class="parameter">$mode</code><span class="initializer"> = 0</span></span>): <span class="type"><span class="type">array</span>|<span class="type">string</span></span></div>

  <p class="para rdfs-comment">
   统计 <code class="parameter">string</code>
   中每个字节值（0..255）出现的次数，使用多种模式返回结果。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.count-chars-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">string</code></dt>

     <dd>

      <p class="para">
       需要统计的字符串。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">mode</code></dt>

     <dd>

      <p class="para">
       参见返回的值。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.count-chars-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   根据不同的   <code class="parameter">mode</code>，<span class="function"><strong>count_chars()</strong></span>
   返回下列不同的结果：
   <ul class="itemizedlist">
    <li class="listitem">
     <span class="simpara">
      0 - 以所有的每个字节值作为键名，出现次数作为值的数组。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      1 - 与 0 相同，但只列出出现次数大于零的字节值。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      2 - 与 0 相同，但只列出出现次数等于零的字节值。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
      3 - 返回由所有使用了的字节值组成的字符串。
     </span>
    </li>
    <li class="listitem">
     <span class="simpara">
     4 - 返回由所有未使用的字节值组成的字符串。
     </span>
    </li>
   </ul>
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.count-chars-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
      <td>8.0.0</td>
      <td>
       在此版本之前，函数在失败时返回 <strong><code>false</code></strong>。
      </td>
     </tr>

    </tbody>
   
  </table>

 </div>


 <div class="refsect1 examples" id="refsect1-function.count-chars-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4757">
    <p><strong>示例 #1 <span class="function"><strong>count_chars()</strong></span> 示例</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$data&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"Two&nbsp;Ts&nbsp;and&nbsp;one&nbsp;F."</span><span style="color: #007700">;<br /><br />foreach&nbsp;(</span><span style="color: #0000BB">count_chars</span><span style="color: #007700">(</span><span style="color: #0000BB">$data</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">)&nbsp;as&nbsp;</span><span style="color: #0000BB">$i&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">$val</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"There&nbsp;were&nbsp;</span><span style="color: #0000BB">$val</span><span style="color: #DD0000">&nbsp;instance(s)&nbsp;of&nbsp;\""&nbsp;</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">chr</span><span style="color: #007700">(</span><span style="color: #0000BB">$i</span><span style="color: #007700">)&nbsp;,&nbsp;</span><span style="color: #DD0000">"\"&nbsp;in&nbsp;the&nbsp;string.\n"</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
There were 4 instance(s) of &quot; &quot; in the string.
There were 1 instance(s) of &quot;.&quot; in the string.
There were 1 instance(s) of &quot;F&quot; in the string.
There were 2 instance(s) of &quot;T&quot; in the string.
There were 1 instance(s) of &quot;a&quot; in the string.
There were 1 instance(s) of &quot;d&quot; in the string.
There were 1 instance(s) of &quot;e&quot; in the string.
There were 2 instance(s) of &quot;n&quot; in the string.
There were 2 instance(s) of &quot;o&quot; in the string.
There were 1 instance(s) of &quot;s&quot; in the string.
There were 1 instance(s) of &quot;w&quot; in the string.
</pre></div>
    </div>
   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.count-chars-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.strpos.html" class="function" rel="rdfs-seeAlso">strpos()</a> - 查找字符串首次出现的位置</span></li>
    <li class="member"><span class="function"><a href="function.substr-count.html" class="function" rel="rdfs-seeAlso">substr_count()</a> - 计算字串出现的次数</span></li>
   </ul>
  </p>
 </div>

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